FIG. 18 shows one example of a conventional structure wherein terminals are installed on a circuit board. In the structure illustrated in this diagram, terminal 9 has a thin plate shape and is made from metal, and it comprises a connecting end 9a and a non-connecting end 9b. The connecting end 9a is soldered to the circuit board 1E, whilst the non-connecting end 9b projects externally from the circuit board 1E. By adopting a composition of this kind, it is possible to bend the aforementioned non-connecting end, if necessary, as indicated by the imaginary line in the diagram, and this is convenient for making the non-connecting end 9b into the electrode of a cell, or the terminal of a further circuit board, or the like.
Since the task of soldering the aforementioned terminal 9 to the circuit board is carried out manually by an operator, the work efficiency is poor. Therefore, conventionally, reflow soldering has been adopted as a method for soldering the aforementioned terminal 9. This reflow soldering method comprises a step of coating solder paste onto the surface of the circuit board 1E, a step of superimposing the aforementioned connecting end 9a over the region of the board coated with the solder paste, and a step of heating and melting the aforementioned solder paste, and this sequence of steps can be automated.
However, in the prior art, the following problems occur when the connecting end 9a is soldered to the circuit board 1E by means of a reflow soldering method.
Namely, as shown in FIG. 19 for example, in a case where the two end regions 9c, 9d of a terminal 9A of a set length are superimposed on two regions 35, 35 coated with solder paste, a self-alignment effect is obtained. This is due to the fact that when the solder paste in the aforementioned two regions 35, 35 coated with solder paste are heated and melted, the surface tension of the molten solder acts respectively on each end region 9c, 9d, and a force aligning the whole of the terminal 9A with the aforementioned two solder paste coated regions 35, 35 is exhibited. In order to obtain a self-alignment effect in this way by using a reflow soldering method, it is necessary for the surface tension of the molten solder to act on the terminal at a plurality of points.
However, in the structure illustrated in FIG. 18, only connecting end 9a of the aforementioned terminal 9 is soldered to the circuit board 1E, and therefore the surface tension of the molten solder only acts on this portion of the terminal. Therefore, in the prior art, in a case where the aforementioned terminal 9 is installed on the circuit board 1E, a problem arises in that no self-alignment effect is obtained and therefore positional accuracy of the terminal 9 declines.
Conventionally, as means for raising the positional accuracy of the terminal 9, pins for registering the location of the terminal 9 may be provided on the circuit board 1E. However, in the case of means of this kind, the aforementioned pins present an obstacle when installing the terminal 9 on the aforementioned circuit board 1E, and there have been instances where automatic installation of the terminal 9 by means of an automatic mounting device has been difficult to implement. Moreover, problems have also arisen in that the task of providing the aforementioned pins on the circuit board 1E in advance is complicated.